We’re in a private room at the back of a private members’ club in Shoreditch, east London, where Robert Pattinson is sitting on a comfy-looking sofa wearing tight black jeans and a tight white T-shirt. We’re about as cloistered from the bustle of real life as you’re likely to get in the capital, which is kind of the point.

“I’m still quite nervous in public,” says Pattinson. “People want to come up and talk to you, but I’ve never really found a way to cope with that. A lot of celebrities have this kind of protective psychic shield,” he explains, waving his hands in front of his face. “I still haven’t developed one.”

If this strikes you as a little precious — as just some “boo hoo hoo, the price of fame”-type whinge — then I would like to make the case that there are grounds for cutting Pattinson some slack. For a start, we have to consider how he got here in the first place.

So an untrained 21-year-old actor from west London lands a lead role in an adaptation of the Twilight young adult novels, novels that concern sexy, angsty teenage vampires. Over the course of five films starting from 2008, The Twilight Saga is established as one of the most lucrative movie franchises, helping Pattinson become both incredibly wealthy (he is now worth a reported £65 million) and incredibly desired (he was voted Glamour magazine’s sexiest man in the world for four years on the bounce). Millions start referring to him as R-Patz.

Already, that’s pretty disorientating, but just to make things even more intense, he then fell into a real-life relationship with his on-screen love interest, the actress Kristen Stewart. The relationship ended very publicly and very messily in 2013 after it was revealed that she had cheated on him with a Hollywood film director. To avoid photographers and obsessive fans, he spent a lot of time either a) in disguise or b) holed up inside his enormous LA mansion. That was basically Pattinson’s twenties.

He says the period was impossible to get his head around. “Even when it was happening, I didn’t know what was happening,” he says. “I remember when I was 21 and promoting the first Twilight film, I was still toying with the idea of going to university afterwards. I wanted to do international relations. But then it just kind of . . .” he trails off.

It just kind of became Twilight? “Yeah. And you become more invested. Inevitably.” It’s three years since the franchise ended, and I ask if he has a bit more perspective on the ways it changed his life? “No,” he says, chuckling. “I don’t think I’m ever going to have any perspective on it.”

The other reason I’m inclined to let Pattinson get away with talk of “protective psychic shields” is that when it comes right down to it, he’s just really, really likeable. He is considerably more likeable than an incredibly handsome 29-year-old multimillionaire has any right to be. He pokes fun at himself constantly. At times he’ll break into giddy, back-of-the-classroom style giggles. The joke is invariably himself.

He says he has “so many neuroses” including, but not limited to, a “constant fear of being found out and humiliated” as an actor. “A month before I start a job, my entire mind falls apart,” he says, explaining that he can’t help imagining the “unfathomable depths of disaster” he will surely find himself in. He is surprised that, post-Twilight, people are offering him jobs. “It’s so difficult not to just think that you’re a fraud.”

On the one hand, you can take one look at this and think, yeah, classic case of imposter syndrome: these are the nagging doubts of someone who frets that they’ve fluked a career on the strength of their cheekbones and ability to look brooding. The problem with this theory is that, since Twilight finished, Pattinson has worked with heavyweight directors including David Cronenberg and Werner Herzog. These are men who presumably know a halfway decent actor when they see one. The result, I think, is that Pattinson is now a little bit confused about who he is and what he’s about.

He explains how, when doing endless interviews for the Twilight films, “I would sort of deliberately s*** on myself.” He’d get so worried that he’d come across as pompous or big-headed when talking about his job that he’d go in completely the other direction, telling interviewers: “Oh, I don’t really know what I’m talking about.” Afterwards, he’d feel he had sold himself short. “I’d think: ‘I’ve got to stop saying that.’ Because people take it at face value. If you say that you have no idea what you’re talking about, people tend to believe you.”

Pattinson grew up in Barnes, where he attended the Harrodian School. His dad ran a business selling vintage cars and his mum worked booking models. As a teenager he sang in a local band — Bad Girls — and joined a local theatre group with the primary intention of meeting, well, girls. “It wasn’t like I was a kid who just loved having the spotlight on him,” he says. “That’s not part of my character.”

It sounds like a comfortable upbringing rather than a gilded one. You wonder whether if he’d been just a little bit posher — proper posh rather than just posh for the suburbs — he’d be a lot more at ease with his success. His family, as he describes them, sound a lot like him: very English, very unobtrusive. “We’re terrible at getting a barman’s attention,” he says, by way of example. “With the exception of my mum, who is completely fearless, we’ll just stand there for hour after hour getting more and more furious, but the anger is never enough to make you raise your voice.”

In a roundabout way, though, this probably helped his career. He is about to appear in Life, a film by the Dutch director Anton Corbijn. He plays Dennis Stock, a photographer for Life magazine who becomes friends with James Dean (played here by Dane DeHaan). Pattinson expresses both amazement at and admiration for the way that Dean was a rebel not just on screen, but within Hollywood.

“Did you know that he didn’t show up to the premiere of his first film? He literally just . . . didn’t go,” he says, frowning. “I’m so envious of people who can do things like that. It’s just that I’m waaaaay too afraid of the consequences to do them myself.”

Hollywood, he explains, has always been a very feudal place. It’s just that he thinks the power now rests with the small number of talent agencies rather than the big studios. “You can p*** off the wrong person and then that’s it, you’re done,” he says starkly. “You’re screwed. I know actors who have had that happen to them. It’s a really easy thing to do because there are a lot of sensitive people in this industry.”

Unwittingly upset the wrong power-broker at the wrong agency and doors suddenly shut in your face. “There will be a company line: ‘This guy is no good’,” he says. “It’s very regimented.” So while Dean wouldn’t last five minutes today, polite, self-effacing boys from Barnes are probably pretty well suited to such things.

He says he has recently “kind of” moved back to the UK after eight years in LA. The unspoken implication is that he moved back to be with his girlfriend, the singer Tahliah Barnett — better known by her stage name of FKA twigs — who lives in east London. I say “unspoken” because Pattinson has a policy of not answering questions about her or even acknowledging their relationship. However, they are obviously going out because there are loads of photographs of them holding hands and appearing at events together, which is always a bit of a giveaway.

Anyway, he seems genuinely happy to be back in London. For one thing, this is where most of his mates are. “I’ve basically had the same core group of friends since I was 13. Some people make new friends when they go to college or whatever, but when you’re an actor making new friends is quite difficult because you never spend enough time in one place. I’ve ended up being quite reliant on the friends I’ve always had.”

I get the impression Pattinson’s keen to start doing the stuff that most 29-year-olds do. He says he would “love to start a five-a-side football team”. He talks about his favourite YouTube video, a three-second clip of a kid taking a penalty that hits the goalkeeper in the face (“God, I must sound like such a moron”). Apparently he went through a phase of using the Headspace guided meditation app, stopped doing it but still gets woken up by preset reminders telling him it’s time for some mindfulness. “It’s like it’s taunting me,” he says.

He has also grown a beard. Sorry, I should probably have mentioned this earlier on but, yeah, he has a massive beard. And not an artfully dishevelled hipster one, but a properly bushy, park-bench-cider-drinker-type effort. He’s grown it for a forthcoming role in a film about British explorers trying to find a lost city in the Amazon rainforest. To acquire the necessary physique he says he’s been hitting the gym and he complains — a little unconvincingly — about his slowing metabolism.

“I’m so glad about the vanity required in this job because if I didn’t have to stay in shape, I’d be such a fat arse,” he says, “but it used to be that I could start working out four weeks before a job and it would be totally fine. Now? Nothing happens. You just beat your body into submission. What the f*** is going on? I had to go on holiday to an extravagant secret location this year because I was afraid of someone photographing my gut.”

Still, people are asking him to be in their films, so that’s good. Deep down I think Pattinson is edging towards the conclusion that he might be a decent actor after all. “I’m not fully there yet, though,” he says, quickly. “It’s still hard for me to say ‘This is who I am! This is my voice!’, but I think the most embarrassing thing would be if that fear of humiliation stopped you from doing what you actually wanted to do. And then you look back on it afterwards and think, ‘What the f***? What was the worst thing that was going to happen?’ ”